Method of and apparatus for kiln-drying lumber



July 29, 1924. 1,503,168

M. L. MUELLER METHOD OF AND APPARATUS FOR KILN DRYING LUMBER Filed ADril 21 1923 2 Sheets-Sheet l I I l I I I l I l I I l I l l I I I I I l I I l l I I l l I l I l l I I I I I I I I I I l l l I l I I I I I I l gwvwntoz Now- L.Mue1/en July 29 1924.

1.503.168 M. 1.. MUELLER METHOD OF AND APPARATUS FOR KILN DRYING LUMBER Filed Avril 21 1923 2 Sheets-Sheet 2 'nmnuunt z:

" nun nun nun. nun

16. 16 nuudnny q 30 llllllllllllllllllm l| AV E III! I 4 0 15 I 1 M09133 LQMBLBIJGX Patented July 29, 1924.

UNITED STATES PATENT OFFICE.

moarrz L. mum or wasume'ron, assrouoa T nomawnsr BLOWER ,KILN comrmv, or smut-ma, wasnmeron, A coaroxwrron or wasmne'ron.

METHODOF AND APPARATUS FOR K ILN-DRYING LUMBER.

Application filed April 21, 1923. Serial No. 683,688.

To all whom it may concern:

Be it known that I, Monrrz L. MUELLER, a citizen of the United States of America,

and residentof the city of Seattle, in the county of King and State of \Vashington,

have invented certain new and useful Improvements in Methods of and Apparatus forKil-n-Drying Lumber, of which the following is a speclfication.

My invention relates to kilns for drying lumber, and particularly to a kiln which is designed to dry lumber while piled on edge. The object of my invention is to provide a method and means for drying lumber in this way, which will in some respects be simpler and which also will be more efl'ective thanthe previous methods and apparatus employed for this purpose.

My invention comprises not only a new method for operating kilns and drying lumber, but the construction of the .kiln itself by whiclrtllis method may be carried out.

The novel features of my invention which I believe to be new and upon which I desire to secure a patent will be particularly defined in the claims terminating this specification.

The accompanying drawing shows a type of construction for the apparatus which I now desire to use.

' Figure 1. is a transverse sectional elevation of a kiln constructed in accordance with my invention.

Figure 2 is a'horizontal or sectional plan taken above the rail line of the kiln.

Figure 3 is a longitudinal sectional elevation taken approximately on the line 33 of Figure 1.

Figure 4: shows a typical section lengthwise of one of the air discharge flues.

The-kiln proper, 1, may consist of any suitable type of construction which provides a kiln chamber of such size as will accommodate the loads placed upon the trucks and at the same time leave suitable circulating s'iaces or flues about the load of lumber. 'l he trucks upon. which the lumber is placed for drying are loaded with the lumber piled on edge. The piling of the lumber upon the trucks will be in accordance with previous ractice, in which the successive layers of umber are spaced apart by thin strips so as to make a vertical air circulating channel the trucks run, and below a flooring which as herein shown in below the'level of the rails,

is constructed a flue 14 into which air is withdrawn from the kiln chamber through a series of holes 16, which holes are made-as slots and which are smaller in cross sectional area near the end which isconnected tothe fan 3, shown in Figures 2 and 3. I have shown the fan which produces the circulation as being located at one end 'of the kiln and beneath the trackway. This particular location is, however, not essential. The fan may be located at one side of the kiln or wherever it is found practical and conveni ent to locate it.

An air re-heating chamber 30 is provided in which the air withdrawn from the kiln through the flue'14 is re-heated. It is then discharged from the fan through flues 15 located at each side of the kiln and provided with discharge openings 4, shown in the form of slots extending crosswise of the flue. These slots are placed so as to run close up to the side of the kiln so that air discharged therefrom will be discharged directly into the flue 10 formed at the sides of the pile of lumber. 1

To control the amount of air which is discharged from individual slots, deflecting .plates 40 are employed. These plates areof,

sheet metal and approximate to an L-shape. The lower or base section" of the L is osi-' tioned inward from the upper wall 0 the flue and extending towards the direction from which the air comes; In other words this base section of the deflector extends into the current of air.. They will each act. to catch a portion of the air. and discharge it through the opening 4. If the air being discharged through one of these openings is not sufficient it may be increased by bendin the plate backward so as to throw the point of the lower arm or base of the deflector farther away'from the roof of the flue. If, however, the amount of air discharged through one of these openings is too much this can be reduced by bending upward the inner end of the deflector, as has been shown in connection with one of the deflectors in Figure 4.

The adjustability of the deflector plates makes it possible to control the rate of discharge from the fiues throughout the length of the kiln thereby securing such a drying rate as conditions dictate. This rate of discharge may be made. even or variable at different points.

I prefer to provide the kilns also with air discharge openings 13 by which a small portion of the air may be discharged, The amount of air discharged may be compensated for by taking in a like amount of air at the fan or at any other convenient point in the circulating system. c

Incarrying outthe system for which this kiln has been designed the air is drawn from the kiln through the flue 14. This --flue is ofsuch width and has its openings 16 so placed well under or inward from the side edges of the pile of lumber, that its thrust action to pass air downward through the layers of lumber is upon that portion of the pile which forms a broad zone e tendingat each side of the center. the discharge of air from the fines 15 directlyupward into the 'fiues 10 between the lumber and the wall of the kiln. in

duces some of the air which has been flowing downward from the lumber near its outer side edges, toflow outwardly and join the air discharged from the flues 15. This portion of the air does not go-periodically back to the re-heaber 30 but is circulated up through the flue 10 and thence is distributed'through the channels of the pile of lumber and is in part at least withdrawn during the next cycle of circulation to the reheater; In consequence of this action the amount of air circulating in the kiln is considerably in excess of the amount passed through the fan. lVhilethe fan handles the larger pant of the air being circulated, part of it is circulated by the inducing action of the air discharged from lines 15 into the flues 10 in the kiln chamber.

This method of operation eliminates the necessity for using baffles beneath the side edges of the lumber pile and increases the volume. of thefcirculating air over the capacity of the fan or equivalent circulating means.

What I claim as my invention is:

1. The herein described method of drying lumber in a kiln which consists in placing the lumber in the kiln in piles having the lumber on edge and with layers spaced apart to provide vertical circulating channels therethrough, and with the top, sides and bottom faces of the pile spaced away from the corresponding walls of the kiln to provide circulation spaces between, withdrawing air from the kiln chamber beneath the piles, reheating the withdrawn air and discharging it upwardly into the kiln at the base of the flues between the lumber piles and the side walls.

2. The method of drying lumber in kilns which consists in placing the lumber within the kiln in piles having vertical circulating channels therein and of a size to leave air circulating passages entirely around the pile, causing a downward" circulation through the pile by withdrawing air through openings located in the kiln floor well inward from the side margins of the pile, reheating the air so withdrawn and dischargingit upward into the spaces between the side "-faces of the lumber pile and the kiln side walls, and thereby inducing part of the air flowing downwardly through the channels in the lumber pile near its side edges to flow laterally outward and join the upwardlv discharged air. Also whi -h consists in placing the lumber within 3. The method of drying lumber in kilns the kilns in'piles having vertical circulating channels therein and of a size to leave air circulating passages entirely around, inducing a downward draft of air through a broad central band of the pile by withdrawing air through the fioor under said band and through the side portions of the pile by discharge of heated air upward into the flues at the side of the pile.

4. A lumber drying kiln comprising a chamber having a trackway extending lengthwise thereof and adapted to receive lumber carrying trucks,. an air-withdrawing flue located between the rails, an air discharging flue at each side of the track, said flues having openings close to the side walls of the kiln "for discharging air upwardly, air reheating means and means for withdrawing air from the kiln through said central flue, passing it through the reheating means and discharging it upwards into the kiln from the side flues.

Signed atSeattle, King County, Washington, this 14th day of April, 1923.

MORITZ L. MUELLER. 

